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gmckey 03-28-2007 12:20 PM

DIY CO2 Working? Initial signs?
I recently (last weekend) finished my DIY CO2 setup for my 55 gal tank using 2 2 liter bottles plumbed to a drip/seperation canister then into an inline filter/canister/diffuser on the filter -> tank line of my Rena XP2. It's been in there about 3 days now and I still haven't seen any visible effects... I figured I would at least see a few bubbles attached to some plants or driftwood or something... but I don't see anything, is there any way I can check to make sure it's working? I'm 100% positive my system has no leaks and is completely water and air tight.


fish_4_all 03-28-2007 03:56 PM

You should see bubbles coming out of the end of the tube and you won't see any water in the tube that goes in the tank anymore. The best way to tell is to simply take the tube and watch for bubbles to come out. If there are none then there is something either wrong with the mix or it hasn't taken off yet which is only really an issue if it is too cold. The mixture should be around 70-85F to get good production, much colder can slow production massively. Also remember that the CO2 is under pressure and leaks can be very hard to find. I sealed mine with silicone and pipe thread tape and still had to modify it to get it completely air tight.

Don't be in too much of a hurry, it can take some time to get going but should produce 50-200 bubbles a minute once it gets going good. 1-2 bubbles a second on average.

gmckey 03-28-2007 04:20 PM

any harm in plumbing a small air pump in line to mix with the CO2?

fish_4_all 03-28-2007 04:39 PM

I am not sure but I think it might have it's potential downfalls. Pressure in the system, gassing out CO2 and possible other things. I don't think it is a good idea but again, I can only speculate as I don't know any facts for sure.

gmckey 03-28-2007 05:11 PM


Originally Posted by fish_4_all
I am not sure but I think it might have it's potential downfalls. Pressure in the system, gassing out CO2 and possible other things. I don't think it is a good idea but again, I can only speculate as I don't know any facts for sure.

It would be plumbed inline AFTER the one way valves isolating the CO2 generators from any added pressurization. It would simply add more oxygen to the water...

fish_4_all 03-28-2007 05:35 PM

It could well work then, and after all, the air we breath does have CO2 in it so it could be adding that also.

I would first get my CO2 running and test for the levels a couple times over a couple weeks to get an idea of where they are. Then add the air pump to it and see what happens. If it drops the levels of CO2 then you have your answers. If not and nothing else negative happens then it could be another revelation in CO2 injection and O2 balance.

Please keep us appraised of your results.

DeMonZ 04-01-2007 07:25 AM

If there are no bubbles coming out of your airlines from the Co2 bottles, either the setup is leaking or the mix isnt working. After, of course, checking for leaks (which you have done), I would look into the mix. It is entirely possible that the yeast you used was dead for whatever reason. This was the case for me on my first attempt. I used some yeast we had here at home (not knowing how old it was) that was dead. I have a friend who also does DIY Co2 and he has bought atleast 2 batches from the grocery store that were dead.

If you're doing your Co2 like most suggest, dead yeast would be evident before adding it to the bottles. This is how I do mine. Use a 1/4 cup of warm water (100F-110F). Add a pinch of sugar and a 1/4 teaspoon of yeast. Stir it well enough to break up all the globs and then let it sit for 10 minutes in the cup. The yeast should start foaming up in the cup, if not, it's dead. It wont foam alot, but will foam none-the-less. While you're waiting on it, add 75F-85F water to your 2-liter bottles and 2 cups sugar to each. I also add a 1/4 teaspoon of baking soda. After 10 minutes (and if foaming), add the mix to the bottles.

2 things I would suggest. One, is adding a bubble counter. It's an easy way to check if your bottles are producing. It also allows you to count bubbles every couple of days to watch for a bottle going dead as there is no set number of days a mix will last.

The other is adding several more bottles to your setup. With only 2 bottles, you'll be lucky to get to 10 or 15ppm Co2. Most "experts" will tell you to get, and stay, above 30ppm. I started out with a 2 2-liter bottle setup on my 55g and averaged about 13ppm. Mine started pushing bubbles out after about 6 hours. However, after a day or so, my tank started turning green from algae. I jumped up to 6 bottles now and still have some algae, but nothing near to what it was with 2 bottles. My problem now is unbalanced ferts. Still trying to figure that part out.

Andrew 04-01-2007 10:56 AM

adding o2 displaces CO2- so yes it does effect in a negative way.

fish_4_all 04-01-2007 03:01 PM

CO2 and O2 saturations are independant of each other and saturations will not be affected by either. It will be dependant on your KH as to what your CO2 saturation will be. If it is low, below 2dKH then your CO2 levels will be low. Your dKH should always be above 3 and this will help to keep your CO2 levels where they need to be. Mine is regularly 6-7 and my CO2 levels are above 15ppm without CO2 injection and running an airstone in the tank.

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